Q: My sister told me my nephew was born without an ear canal. Please tell me about this condition.

A: The outer part of the ear helps channel sound waves into the ear canal. Sound waves then hit the eardrum (part of the inner ear) causing it to move. All this is considered the “conductive” part of hearing.

This eardrum motion is subsequently sensed by cells in the inner ear, stimulating electric signals. These signals are then transferred to an area of the brain where they are processed and interpreted. All this is considered the “sensory” aspect of hearing.

The ear canal begins in the outer part of the ear, where it is surrounded by cartilage, and continues deeper to the inner ear where it is surrounded by bone. The development of the ear canal occurs during the fifth and six months of gestation.

Aural atresia (also called external auditory canal atresia) is a rare congenital disorder (1 in 10,000 children are born with it) where the ear canal does not develop normally. Three-quarters of the time this is only on one side; the remaining 25 percent of cases have bilateral aural atresia. For some patients, the ear canal is simply abnormally narrow; others have a complete lack of canalization. A CT scan can help characterize the extent the canal is compromised.

Fetal exposure to toxins, infections and/or trauma as well as low birth weight are known risk factors for aural atresia. There may also be a hereditary component, and some cases are associated with other congenital conditions. However, in most cases the cause of aural atresia is not known.

Aural atresia is typically identified during the newborn physical exam. Since other organs, such as the heart, kidneys and eyes, develop at about the same time as the ears, a detailed evaluation of children with aural atresia is indicated. Occasionally, more subtle cases of aural atresia are not identified until later in childhood.

As would be expected, the lack of an ear canal will compromise conductive hearing. The amount of the hearing compromise depends on how severely the ear canal is affected, as well as if the atresia is in one or both ears. Since hearing is necessary for normal language development, early identification of any hearing defect is vital.

Some patients with aural atresia also have parts of their inner ear affected. In these patients the sensory aspect of hearing will be affected in addition to the conductive aspects.

Most patients with aural atresia have abnormal development of their external ear. This may cause cosmetic concerns and possibly social issues for the child. The extent of the abnormal external abnormalities is very variable from patient to patient.

Since language development is so important early in life, hearing testing for children with aural atresia is extremely important; auditory brainstem response audiometry is used to test hearing in infants. If hearing is significantly compromised, a hearing aid, such as a bone-anchored hearing device, is indicated. The child’s speech development will need to be closely followed.

Page 2 of 2 - Otitis media (colloquially called an ear infection) is common in children, and kids with aural atresia can develop these infections as well. Otitis media is usually diagnosed by identifying a fluid buildup behind the eardrum; this cannot be done in children with aural atresia since the ear canal compromise prevents direct visualization of the eardrum. Therefore, pediatricians caring for patients with aural atresia should maintain a high index of suspicion of an ear infection, and they should treat these kids with antibiotics if one is suspected.

Children with aural atresia should be cared for by a cross functional team including a pediatrician, a hearing specialist, a speech pathologist, a social worker, a psychological counselor and an ENT surgeon who specializes in ear surgeries; if cosmetic surgery is needed (this depends on the extent of the abnormality of the patient’s external ear), a plastic surgeon should also be included on this team. The goals of therapy include ensuring adequate language development and maximizing hearing. Surgery is usually required for kids with bilateral aural atresia, and is also beneficial in certain kids with unilateral disease; surgery is usually done after age six.